318 ALASKAN GLACIER STUDIES a minor interruption of the previous slow retreat, as the increase in snowfall for only one year at a time would suggest; and (c) in affording an opportunity, in case the advance is climatic and is not a small local affair, of seeing how long after an increase in snowfall the general advance begins and for what period of years it continues. In the latter case the advance might go on for some considerable part of the period of 35 to 50 years observed in many glaciers of the Alps and other mountain regions.1 It is especially interesting as possibly yielding future data in connection with the 35 year periods described by Brilckner.2 It would be most desirable if some one could revisit the Unakwik Inlet and College Fiord glaciers and the others in Harriman Fiord and the remainder of western Prince William Sound after a few years to gather information on this important question. i Ford, A., Jahrbuch des Schw. Alp. Verein, Annual volumes beginning in 1881. Rabot, C., Revue de Glaciologie, Ann. du dub alpin Francais, Vol. -3LX.VLL1, Paris, 1902; Ibid., No. 2, Op. cit., Vol. YXTX, Paris, 1003; Ibid., No. 3, M&noires de la Socie'tfi Flibourgeoise des Sciences naturelles, Vol. V, Fribourg, 1909. Finsterwalder, S., Comptes rendua du Congres geologique international, de Vienne, 1903, pp. 161-169. Reid, H. F., Variations of Glaciers, Jour. Geol., Vol. HE, 1895, pp. 278-288; and annually since then in the Journal of Geology. See also the annual volumes of the Zeitschrift ftlr Gletscherkunde. Brtlckner, Eduard, La Commission Internationale des Glaciers au Congres geologique international, Stockholm, aout, 1910, Zeitschrift ftlr Gletscherkunde, Band V, 1911, pp. 161-176. * Brtlckner, Eduard, Elima-Schwankungen eeit 1700, Geog. Abhand. von Dr. Penck, Band IV, Wien, 1890, pp. 133-198.